The NIC has to deal with drivers and passing information up the network stack to an OS, which could be Windows, Linux, MacOS, some weird esoteric device, etc. It has to assign a MAC address to those ports, an IP address, and all kinds of other overhead and data management. Also has to have a connector; PCI, USB, some other type of interface to the system.
The switch can keep everything in happy Layer 2 / 3 land, and never has to deal with an OS, just shuffling packets around. Scaling this to multiple ports is far more simple.
The NIC has to deal with drivers and passing information up the network stack to an OS, which could be Windows, Linux, MacOS, some weird esoteric device, etc. It has to assign a MAC address to those ports, an IP address, and all kinds of other overhead and data management. Also has to have a connector; PCI, USB, some other type of interface to the system.
The switch can keep everything in happy Layer 2 / 3 land, and never has to deal with an OS, just shuffling packets around. Scaling this to multiple ports is far more simple.